1. Field of the Invention
This invention relates to valve apparatus for pressurized irrigation systems and, more particularly, to a valve apparatus and method for controlling flow of water to an end gun of a pivot irrigation system.
2. The Prior Art
Within the past few decades, pressurized irrigation systems have been developed to allow for distribution of water to food and forage crops on lands which would otherwise be unsuitable for irrigation farming due to insufficient water, undulating or otherwise unsuitable terrain, etc. Various pressurized irrigation systems are known and include stationary systems, laterally movable systems, and pivotal systems. Of the foregoing, the pivotal system is generally preferred since it is essentially automatic and does not require periodic lateral shifting of the irrigation system to distribute the water uniformly over a relatively larger sector of land.
The conventional pivot irrigation system consists of an elevated, wheel-mounted conduit with a plurality of sprinklers mounted thereto at spaced locations. One end of the pivot irrigation system is connected through a swivel joint to a source of pressurized water. The wheels of the system are driven by electrical motors and each set of wheels along the length of the conduit are turned at a predetermined rate to accommodate pivotal movement of the pivot irrigation system in circular path around the central swivel. The overall pivot irrigation system is generally hundreds of feet long and will serve to distribute thousands of gallons of water in a single sweep over a large circular area consisting of many acres.
Since the outer or opposite end of the pivot irrigation system moves across a greater arcuate distance and since it is usually desirable to extend the area of coverage of the pivot irrigation system as much as possible, it is common practice to mount a large nozzle apparatus on the end of the pivot irrigation system. This large nozzle apparatus is called an "end gun" and is configurated to dispense substantially larger volumes of water than any of the individual sprinklers along the length of the pivot irrigation system. However, this large volume of water dispensed by the end gun is known to be wasteful as well as detrimental under certain conditions. For example, if the end of the pivot irrigation apparatus passes adjacent an uncultivated field or roadway, the water distributed thereto is wasted.
Although a limited amount of water waste can be tolerated, damage resulting from uncontrolled water distribution can be a serious problem. For example, certain crops in the adjacent field may be ruined by being watered at the wrong time. Also, the water deluge has been known to undermine, flood, and otherwise erode adjacent roadways. The deluge from the end gun has also been a causative factor for damage resulting from accidents involving vehicular traffic travelling along the adjacent roadway.
For these latter reasons, local governmental bodies have legislated restrictions on the operation of pivot irrigation systems adjacent roadways. The value of the pivot irrigation system is thereby lowered since its use in an essentially automatic mode is restricted. For example, an operator is frequently required to be in attendance when the movement of the pivot irrigation apparatus brings the end gun adjacent the roadway. The operator must be present to shut off the end gun and, subsequently, turn the end gun on again when the movement of the system carries the end gun away from the roadway. While this particular method of operation is feasible, it is (1) undesirable, (2) results in wasted man hours, and (3) tends to be unreliable.
In view of the foregoing, it would be an improvement in the art to provide a control apparatus for controlling the flow of water to the end gun of a pivot irrigation system. It would also be an improvement in the art to provide a control valve apparatus and method for controlling the flow of water to an end gun of a pivot irrigation apparatus wherein the flow of water is automatically stopped and started at predetermined locations in the arcuate sweep of the pivot irrigation apparatus. Such a novel apparatus and method is disclosed and claimed herein.